Wireless charging coil

ABSTRACT

A wireless charging coil is provided herein. The wireless charging coil comprising a first stamped coil having a first spiral trace, the first spiral trace defining a first space between windings, and a second stamped coil having a second spiral trace, the second spiral trace defining a second space between windings, wherein the first stamped coil and second stamped coil are planar to and interconnected with one another, such that the first stamped coil is positioned within the second space of the second stamped coil, and the second stamped coil is positioned within the first space of the first stamped coil.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of, and claims priorityto, U.S. Non-Provisional patent application Ser. No. 14/470,381, filedAug. 27, 2014, which claims the benefit of U.S. Provisional PatentApplication No. 61/908,573 filed on Nov. 25, 2013, and U.S. ProvisionalPatent Application No. 62/004,587 filed on May 29, 2014, the entiredisclosures of which are expressly incorporated herein by reference.

BACKGROUND Field of the Disclosure

The present disclosure relates to a wireless charging coil and methodsfor manufacturing thereof. More specifically, the present disclosurerelates to a bifilar parallel wound, series connected wireless chargingcoil.

Related Art

Wireless power transfer is the transfer of electrical power from a basestation (transferring power) to a mobile device (consuming power)through electromagnetic induction (inductive power) and/or resonantfrequency method. Wireless power transfer is becoming increasinglypopular in mobile devices, and particularly in smartphones. A popularstandard for inductive charging technology is the Qi interface standarddeveloped by the Wireless Power Consortium, which has several protocolsto allow the wireless transfer of electrical power between electronicdevices. Other standards may make use of electromagnetic induction orresonant frequency to wirelessly charge devices. A mobile device (or anyother electronic device) must meet certain requirements and performancestandards in order to be Qi compliant.

Consumers generally want their mobile devices to be small and thin butalso powerful and efficient, which are often counteracting goals. Morespecifically, charging coils must vary the material thickness to lowerresistance and increase efficiency. Further, maximizing these goals canlead to performance and manufacturing limitations.

What would be desirable, but has not yet been developed, is a thinnerand more efficient wireless charging coil for wireless power transferbetween electronic devices.

SUMMARY

The present disclosure relates to wireless charging coils and methodsfor making thereof. More specifically, the present disclosure relates toa planar bifilar parallel-wound, series connected wireless chargingcoil. The coil has a thinner thickness (e.g., low profile), an increaseddensity (e.g., high fill factor), and higher efficiency (e.g., lowerresistance) than conventional wireless charging coils.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing features of the disclosure will be apparent from thefollowing Detailed Description, taken in connection with theaccompanying drawings, in which:

FIG. 1 is a diagram showing processing steps for manufacturing awireless charging coil;

FIG. 2 is a schematic view of a first stamped coil with tie bars;

FIG. 3 is a schematic view of a second stamped coil with tie bars;

FIG. 4 is a schematic view of an assembled coil after the tie bars ofthe first and second stamped coils have been removed;

FIG. 5 is a schematic view of the assembled wireless charging coil withjumpers attached;

FIG. 6 is a close up view of portion A of FIG. 5;

FIG. 7 is a schematic view of an electrical component assembly includinga wireless charging coil and NFC antenna;

FIG. 8 is a schematic view of an assembled wireless charging coil withplanar bifilar coils;

FIG. 9 is a cross-sectional view of a portion of the wireless chargingcoil of FIG. 8;

FIG. 10 is a schematic view of an assembled wireless charging coil withstacked bifilar coils;

FIG. 11 is a cross-sectional view of a portion of the wireless chargingcoil of FIG. 10;

FIG. 12 is a perspective view of an electrical component assembly;

FIG. 13 is an exploded view of the electrical component assembly of FIG.12

FIG. 14 is a perspective view of a resonant coil;

FIG. 15 is a perspective view of a resonant coil assembly;

FIG. 16 is a perspective view of a folded stamped resonant coil;

FIG. 17 is a perspective view of the coil of FIG. 16 partially opened;

FIG. 18 is a perspective view of the coil of FIG. 16 fully opened;

FIG. 19 is an exploded view of a low profile electrical componentassembly; and

FIG. 20 is a perspective view of the filler material of FIG. 19.

DETAILED DESCRIPTION

The present disclosure relates to a wireless charging coil and methodsof making same. As discussed in more detail below in connection withFIGS. 1-7, the stamped metal wireless charging coil comprises a seriesof parallel traces connected in a bifilar fashion. In other words, thewireless charging coil includes first and second coils that areparallel, closely spaced, and connected in series such that the firstand second coils have parallel currents. The first and second coilscould be stacked or planar and connected in series and/or parallel tomeet performance requirements (e.g., electrical requirements, powerrequirements, etc.). The wireless charging coil could be used in anybattery powered device, particularly in mobile devices (e.g.,smartphones, tablets, watches, etc.). The wireless charging coil can bemade to be Qi compliant, but could be adjusted to comply with anywireless transfer protocol. A wireless charging coil with a greateramount of conductive material, such as copper, can be positioned withina given space by varying (e.g., increasing) the thickness of the coil,which increases energy availability. Compared with other wirelesscharging coils, the wireless charging coils described herein exhibit anincreased magnetic coupling effectiveness (e.g., magnetic fieldstrength) and thereby transmit energy at a higher efficiency.

FIG. 1 is a diagram showing processing steps 10 for manufacturing awireless charging coil of the present disclosure. In step 12, a metalsheet is stamped to form a first coil with tie bars. The metal sheetcould be any of a variety of materials suitable for wireless powertransfer (e.g., copper, copper alloy, aluminum, aluminum alloy, etc.).In step 14, a metal sheet (e.g., the same metal sheet or a differentmetal sheet) is stamped to form a second coil with tie bars. In step 16,the first coil is stamped to remove the tie bars. In step 18, the secondcoil is stamped to remove the tie bars. In step 20, the first and secondcoils are assembled together. In step 22, the assembled coil is appliedto a ferrite substrate. In step 24, jumpers (e.g., leads) are attachedto electrically connect the first and second coils in series (e.g., aninside end of the first coil is electrically connected to the outsideend of the second coil via a jumper).

The steps described above could be interchanged, consolidated, oromitted completely. For example, the coils could be stamped withoutfirst forming tie bars, and/or the first and second coils could beapplied directly to the ferrite (without being assembled first), etc.Additionally, the coil could be photo-chemically etched or machinedinstead of stamped, or made by any other suitable manufacturing process.

FIG. 2 is a view of a first stamped coil 30 with tie bars. The firstcoil 30 can be a generally rectangular planar spiral trace 31, althoughthe trace 31 could form any suitable shape (e.g., circular planarspiral). The dimensions of the coil 30 could vary depending on theapplication of the coil 30 (e.g., as used in mobile devices, wearabledevices, cars, etc.). The coil 30 could be of any suitable thickness,such as between 0.003 in. and 0.020 in., etc., but could be thicker forhigher powered applications. The coil 30 could be of any suitableoverall dimensions, such as between 0.25 in. and 4 in. in width and/orbetween 0.25 in. and 4 in. in height. The trace 31 could also be of anysuitable dimensions. For example, the trace 31 could be between 0.005in. and 0.250 in. in width. The dimensions could vary depending onphysical and performance requirements of the mobile device (e.g.,required frequency). The coil 30 could be made of any suitable materialfor wireless power transfer, such as, for example, copper, copper alloy,aluminum, aluminum alloy, tempered copper alloy (e.g., C110), etc.

The trace 31 of the coil 30 revolves around a center any number of times(e.g., 5, 10, etc.), such as to comply with any inductive or resonantpower requirements. The trace 31 spirals to form an inside portion 32 atthe center of the coil 30. As a result, the coil 30 has an inside end 34and an outside end 36. The spaces 38 between the trace 31 are configuredto be wide enough (e.g., 0.0285 in.) to accommodate the second stampedcoil (described in more detail below). Tie bars 40 can be positioned ata plurality of locations throughout these spaces 38 to maintain thegeneral shape of the coil 30 (e.g., prevent unwinding or deformation ofthe shape), such as during transportation of the coil 30 betweenlocations or between stations. The outside end 36 could extend out at anangle, such as a generally ninety degree angle. The inside end 34 andoutside end 36 can be disposed towards the same side of the coil 50 30,but could be at any of a variety of locations in the coil 30.

FIG. 3 is a view of a second stamped coil 50 with tie bars. The secondcoil 50 shares most of the same features and characteristics of thefirst coil shown in FIG. 2. The second coil 50 can be a generallyrectangular planar spiral trace 51, although the trace 51 could form anysuitable shape (e.g., circular planar spiral). The dimensions of thecoil 50 could vary depending on the application of the coil 50 (e.g., asused in mobile devices, wearable devices, cars, etc.). The coil 50 couldbe of any suitable thickness, such as between 0.003 in. and 0.020 in.,etc., but could be thicker for higher powered applications. The coil 50could be of any suitable overall dimensions, such as between 0.25 in.and 4 in. in width and/or between 0.25 in. and 4 in. in height. Thetrace 51 could also be of any suitable dimensions. For example the trace51 could be between 0.005 in. and 0.250 in. in width. The dimensionscould vary depending on physical and performance requirements of themobile device (e.g., required frequency). The coil 50 could be made ofany suitable material for wireless power transfer, such as, for example,copper, copper alloy, aluminum, aluminum alloy, tempered copper alloy(e.g., C110), etc.

The trace 51 of the coil 50 revolves around a center any number of times(e.g., 5, 10, etc.), such as to comply with any inductive or resonantpower requirements. The trace 51 spirals to form an inside portion 52 atthe center of the coil 50. As a result, the coil 50 has an inside end 54and an outside end 56. The spaces 58 between the trace 51 are configuredto be wide enough (e.g., 0.0285 in.) to accommodate the first stampedcoil 30 (described above). Tie bars 60 can be positioned at a pluralityof locations throughout these spaces 58 to maintain the general shape ofthe coil 50 (e.g., prevent unwinding or deformation of the shape), suchas during transportation of the coil 50 between locations or betweenstations. The outside end 56 does not extend out as with the first coil30 (but could). The inside end 54 and outside end 56 can be disposedtowards the same side of the coil 50, but could be at any of a varietyof locations in the coil 50.

FIG. 4 is a view of an assembled coil 170 after the tie bars of thefirst and second stamped coils 130, 150 have been removed. As shown, thefirst and second coils 130, 150 fit into each other. More specifically,the first coil 130 fits into the space formed between the trace 151 ofthe second coil 150, and conversely, the second coil 150 fits into thespace formed between the trace 131 of the first coil 130. However, whenassembled, there are small gaps between the trace 131 of the first coil130 and the trace 151 of the second coil 150 (e.g., 0.003 in., 0.004in., etc.), as discussed below in more detail. As a result, together thefirst and second coils 130, 150 together form a parallel planar spiral.Also shown, the inside end 134 of the first coil 130 is adjacent to theinside end 154 of the second coil 150, and the outside end 136 of thefirst coil 130 is adjacent to the outside end 156 of the second coil150. However, the ends could be any relative distance from one another.This stamping method could have an average space width variation of atleast approximately 0.003 in. for the assembled coil 170. The maximumand minimum variance are dependent on the assembled coil 170 dimensions(e.g., overall height and width).

The tight tolerances and rectangular cross-sectional shape of the traces130, 131 could result in a fill ratio (e.g., 85%) greater than currentindustry coils (e.g., 65%), such as wound coils, etched coils, etc. Forexample, the rectangular cross-sectional shape achieved from stamping(see FIG. 9 below) provides a potentially greater fill ratio than thecircular cross-sectional shape of a round wire (e.g., round copperwire). More specifically, a 0.010 in. diameter insulated round wire(0.009 diameter in. wire with 0.0005 in. insulation) could provide a 65%fill ratio, compared to a stamped coil with a rectangular cross sectionhaving a 0.006 thickness and 0.003 spacing gap. Further, the wirelesscharging coil 170 can operate under higher ambient temperatures thanother current industry wires (e.g., Litz wire), and is not susceptibleto degradation by vibration, shock, or heat. This is partly because thewireless charging coil 170 is made of a single-monolithic conductor(e.g., not a multi-strand wire). This can be compared to the individualstrands of a Litz wire, which has insulation material separating each ofthe individual wire strands which cannot withstand higher temperatures.

FIG. 5 is a view of the assembled wireless charging coil 270 withjumpers attached. Although not shown, a jumper could be attached to thefirst outside end 236. As shown, the inside end 234 of the first coil230 is electrically connected to the outside end 256 of the second coil250 by a first jumper 274. These ends 234, 256 are relatively proximateto one another, and disposed on the same side of the coil 270 to allowfor a short jumper 274. A second jumper 276 is then used to electricallyconnect the inside end 254 of the second coil with the mobile devicecircuitry. The outside end 236 and inside end 254 are relativelyproximate and disposed towards the same side of the coil 270, to providefor a short jumper 276 and for ease of electrical wiring with theelectronic device. The result is a pair of parallel, closely spacedcoils 230, 250 connected in series such that the first and second traces230, 250 have parallel currents (e.g., the currents of each trace are inthe same clockwise or counter-clockwise direction).

When fully assembled with the other components of the electronic device,the inside portion 272 of the assembled coil 270 is insulated (e.g., byplastic and glue) to ensure proper performance. The assembled wirelesscharging coil 270 can have any number of windings, depending uponelectrical requirements. The wireless charging coil 270 could be used inany battery powered device, such as smartphones. The assembled coil 270could be of any suitable overall dimensions (e.g., 1.142 in. width and1.457 in. height, etc.). The coil length could be of any suitable length(e.g., 48.459 in.).

FIG. 6 is a close up view of portion A of FIG. 5. As shown, there arevery small gaps 278 (e.g., voids) between the trace 231 of the firstcoil 230 and the trace 251 of the second coil 250 (e.g., 0.003 in.,0.004 in., etc.), although there could be increased gaps 280 at thecorners to account for the bends in the traces 231, 251 (e.g., such thatthe gap increase alternates). These tight tolerances could result in afill ratio greater than current industry methods.

The assembled wireless charging coil 270 could provide direct current(DC) resistance (ohms), alternating current (AC) resistance, and/orAC/DC resistance ratios at a number of different values depending on thedimensions of the charging coil 270 and material(s) used in constructionof the charging coil. The values could be adjusted to achieve high AC/DCratios to meet induction standards. The coil dimensions could be variedto achieve varying resistance depending on the performancecharacteristics required. For example, for a resistance of 0.232 ohmsusing C110 alloy, the traces 230, 250 could have a cross section of0.0001234 in.² (e.g., 0.005 in. thickness and 0.0246 in. width, or 0.004in. thickness and 0.0308 in. width, etc.), and for a resistance of 0.300ohms using C110 alloy, the traces 230, 250 could have a cross section of0.0000953 in.² (e.g., 0.005 in. thickness and 0.019 in. width, or 0.004in. thickness and 0.0238 in. width, etc.). The stamped wireless chargingcoil 270 can achieve a high trace thickness and/or high overall aspectratio compared to other current industry methods (e.g., printed circuitboard (PCB) etched coils).

FIG. 7 is a view of an electrical component assembly 390 including awireless charging coil 370. More specifically, the wireless chargingcoil 370 is attached to ferrite substrate 392 and in conjunction with anear field communication (NFC) antenna 394 having contact paddles. Thewireless charging coil 370 and NFC antenna 394 could have contact pads(e.g., gold) to connect the wireless charging coil 370 and NFC antenna394 to the circuitry of the mobile device. The assembly comprises afirst jumper 374, a second jumper 376, and a third jumper 377 connectingthe various ends of the coil 370, as explained above in more detail.There could be a film (e.g., clear plastic) over the wireless chargingcoil 370 and NFC antenna 394, with the jumpers 374, 376, 377 on top ofthe film and only going through the film at the points of connection.This prevents accidentally shorting any of the electrical connections ofthe coil 370. Alternatively, the jumpers 374, 376, 377 could beinsulated so that a film is not needed. To minimize space, the wirelesscharging coil 370 is within the NFC antenna 394 with jumpers 376, 377that extend to the outside of the NFC antenna 394. However, the wirelesscharging coil 370 and jumpers 376, 377 could be placed at any locationrelative to the NFC antenna 394.

The total thickness of the assembly could vary depending on variouspotential needs and requirements. For example, the jumpers could be0.05-0.08 mm thick, the film could be 0.03 mm thick, the NFC antenna 394and coil 370 could be 0.08 mm thick, and the ferrite 392 could be 0.2 mmthick for a total wireless charging coil thickness of approximately 0.36mm.

FIG. 8 is a schematic view of an assembled wireless charging coil 470with planar bifilar coils. As discussed above, the wireless chargingcoil 470 includes a first coil 430 (e.g., trace) and a second coil 450(e.g., trace). The assembled coil 470 is manufactured and operates inthe manner discussed above with respect to FIGS. 1-7. The first coil 430and the second coil 450 can have any desired thickness, such as to meetdifferent power requirements. The first coil 430 and second coil 450could be connected in series or parallel.

The width of the first and/or second coil 430, 450 could vary along thelength of the coil to optimize performance of the assembled wirelesscharging coil 470. Similarly, the thickness of the first and secondcoils 430, 450 could change over the length of the coil. For example,the width (and/or thickness) of the first coil 430 could graduallyincrease (or narrow) from a first end 434 towards a middle of the coil430, and the width (and/or thickness) could likewise gradually narrow(or increase) from the middle to the second end 436 of the coil 430(e.g., a spiral coil of wide-narrow-wide), thereby varying thecross-sectional area throughout. Any variation of width (e.g.,cross-section) or thickness could be used, and/or these dimensions couldbe maintained constant over portions of the coil, according to desiredperformance characteristics.

Additionally (or alternatively), the spaces between the windings of thecoil could be varied to optimize performance of the wireless chargingcoil 470. For example, the gap width between the traces could be widertowards the outside of the first coil 430 and narrower towards theinside of the first coil 430 (or the opposite). Similarly, the distancebetween the first coil 430 and second coil 450 in the assembled coil 470could also be varied to optimize performance. Further, the geometry ofthe edges of the coil could be varied (e.g., scalloped, castellated,etc.), such as to reduce eddy currents.

FIG. 9 is a cross-sectional view of a portion of the wireless chargingcoil of FIG. 8. The first coil 430 comprises sections 414-424 and thesecond coil 450 comprises sections 402-412. As shown, the cross-sectionof the first coil 430 becomes gradually wider and then narrower from afirst end to a second end of the first coil 430. As a result, sections414 and 424 are the narrowest (e.g., 0.025 in.), followed by sections404 and 422 (e.g., 0.030 in.), and sections 418 and 420 are the widest(e.g., 0.035 in.). In the same way, the cross-section of the second coil450 becomes gradually wider and then narrower from a first end to asecond end of the second coil 450. As a result, sections 402 and 412 arethe narrowest, and sections 406 and 408 are the widest. Changes in thedimensions of the cross section of the antenna can likewise be varied inother manners.

FIG. 10 is a schematic view of an assembled wireless charging coil 570with stacked bifilar coils. As discussed above, the wireless chargingcoil 570 includes a first coil 530 and a second coil 550. The assembledcoil 570 is manufactured and operates in the manner discussed above withrespect to FIGS. 1-7, as well as that discussed in FIGS. 8-9, exceptthat the first and second coils 530, 550 are stacked instead of planar.The first coil 530 includes a first end 534 and a second end 536, andthe second coil 550 includes a first end 554 and a second end 556.Further, varying the skew or offset (e.g., stacking distance) of thefirst coil 530 relative to the second coil 550 can affect theperformance of the wireless charging coil 570. The first coil 530 andsecond coil 550 could be connected in series or parallel.

FIG. 11 is a cross-sectional view of a portion of the wireless chargingcoil of FIG. 10. This coil 570 is similar to that of FIGS. 8-9,including a first coil 530 with sections 514-524 and a second coil 550with sections 502-512, except that the first and second coils 530, 550are stacked instead of planar.

FIGS. 12-13 are views showing an electrical component assembly 690. Morespecifically, FIG. 12 is a perspective view of an electrical componentassembly 690. The electrical component assembly 690 comprises a ferriteshield 692, a pressure sensitive adhesive (PSA) layer 602 positioned onthe ferrite shield 692, an assembled coil 670 (e.g., bifilar coil)positioned therebetween, and jumpers 674, 676 positioned on the PSAlayer 602.

FIG. 13 is an exploded view of the electrical component assembly 690 ofFIG. 12. The bifilar coil 670 includes a first coil 630 having an insideend 634 and an outside end 636 interconnected with a second coil 650having an inside end 654 and an outside end 656. The inside and outsideends are on the same side of the assembled coil 670 for ease of use andassembly (e.g., minimize the distance to electrically connect the ends).

Ferrite shield 692 includes a first hole 696 and a second hole 698positioned to correlate with the placement of the inside end 634 of thefirst coil 630 and the inside end 654 of the second coil 650 (e.g., whenthe coil 670 is placed onto the ferrite shield 692. Although holes 696,698 are shown as circular, any shape and size openings could be used(e.g., one rectangular opening, etc.). These holes 696, 698 facilitateassembly and welding of the electrical component assembly 690.

PSA layer 602 and ferrite shield 692 are similarly sized to one another,and although shown as rectangular, both could be of any shape (e.g.,circular). PSA layer secures the relative placement of the assembledcoil 670 to the ferrite shield 692. PSA layer 602 could have adhesive onone or both sides, and could include a polyethylene terephthalate (PET)film area 604 free of adhesive on one or both sides. PET film area 604facilitates assembly and welding of the electrical component assembly690.

PSA layer 602 includes a first hole 606 and a second hole 608 in the PETfilm area 604 which correlate in position with the placement of theinside end 634 of the first coil 630 and the inside end 654 of thesecond coil 650 (as well as the first hole 696 and second hole 698 ofthe ferrite substrate 692). Although holes 606, 608 are shown ascircular, any shape and size openings could be used (e.g., onerectangular opening). Holes 606, 608 provide access through the PSAlayer 602 to electrically connect jumpers 674, 676 with the inside ends634, 654 of the assembled coil 670. The PET film area 604 facilitatesattachment of the jumpers 674, 676 to the assembly 690.

FIG. 14 is a perspective view of a resonant coil 730. Resonant coil 730could be a generally rectangular planar spiral trace 731, although thetrace 731 could form any suitable shape. The resonant coil 730 includesan inside end 734 and an outside end 736. The trace 731 is stamped on astrip or sheet of metal (e.g., copper, aluminum, etc.). The dimensionsof the coil 730 could vary depending on the application of the coil 730.The coil 730 could be of any suitable thickness, and of any suitableoverall dimensions. The trace 731 could also be of any suitabledimensions. The dimensions could vary depending on physical andperformance requirements. The coil 730 could be made of any suitablematerial for wireless power transfer, such as, for example, copper,copper alloy, aluminum, aluminum alloy, tempered copper alloy (e.g.,C110), etc. The gaps between the windings of the trace 731 are largerfor a resonant coil than for other types of inductive coils due toperformance requirements.

Stamping provides a scalable process for high volume production withhigh yields. The stamped trace 731 is not prone to unwinding and canallow for a thicker trace. This is advantageous compared with otherexisting technologies. For example, winding wire (e.g., copper) to aspecific pattern on a surface is difficult and the wound wire canunwind. Further, etched copper is expensive and could be limited to amaximum thickness (e.g., 0.004 in. thick).

The trace 731 of the resonant coil 730 includes a first side 737 and asecond side 739 offset from the first side 737 by angled portions 741 ofthe trace 731. The angled portions 741 are aligned with one another(e.g., occur along line B-B), and angled in the same direction. In otherwords, angled portions 741 are all angled toward a particular side ofthe coil 730 (e.g., towards one side of line A-A), such that a firstportion 737 (e.g., upper portion) of the coil 730 is shifted relative toa second portion 739 (e.g., lower portion) of the coil 730.

FIG. 15 is a perspective view of a resonant coil assembly 790, includingthe first resonant coil 730 from FIG. 14. The resonant coil assembly 790includes a first coil 730 and a second coil 750, which are identical toone another (which minimizes manufacturing costs). The resonant coilassembly 790 could be laminated such that the first coil 730 and secondcoil 750 are laminated to a film 702 (e.g., PET film), such as by anadhesive (e.g., heat activated, pressure sensitive, etc.) to providemore stability in downstream operations. The first coil 730 could beadhered to one side of the film 702 and the second coil 750 could beadhered to the opposite side of the film 702.

The first coil 730 includes an outside end 736 and an inside end 734,and the second coil 750 includes an outside end 756 and an inside end754. The first coil 730 and second coil 750 could be exactly the samesize and shape coil, except that the second coil 750 is rotated 180degrees about line D-D. In this way, the trace 731 of the first coil 730is positioned between the gap formed by the windings of the trace 751 ofthe second coil 750 (and vice-versa), except at the angled portions ofeach coil along line D-D, where the traces cross one another. The insideend 734 of the first coil 730 could be adjacent to (and in electricalconnection with) the inside end 754 of the second coil 750, and theoutside end 736 of the first coil 730 could be adjacent to the outsideend 756 of the second coil 750.

FIGS. 16-18 are views of a stamped resonant coil 870. FIG. 16 is aperspective view of a folded stamped resonant coil 870. The coil 870comprises connector sheet 871, a first set of traces 831 of a first coilportion 830 with ends thereof connected to an edge of the connectorsheet 871 at connection points 873, and a second set of traces 851 of asecond coil portion 850 with ends thereof connected to the same edge ofthe connector sheet 871 at connection points 873. To create the stampedresonant coil 870, a (single) sheet of metal is stamped to form thefirst set of traces 831 and the second set of traces 851 (e.g., suchthat the arcs of each trace of the first and second sets of traces 831,851 are oriented in the same direction). The ends of the first andsecond set of traces 831, 851 are then connected to the same edge ofconnector sheet 871 (e.g., insulation material). The connector sheet 871facilitates wiring of the sets of traces 831, 851 to each other, as wellas facilitates the connection of the stamped resonant coil 870 toelectronic circuitry. The ends of the first and second set of traces831, 851 are then wired to each other, such as by using a series ofjumpers and/or traces. For example, the jumpers and/or traces could bein the connector sheet 871 and could run parallel to the connector sheet(and perpendicular to the first and second sets of traces 831, 851).

FIG. 17 is a perspective view of the coil 870 of FIG. 16 partiallyopened. As shown, the first set of traces 831 of the first coil portion830 are bent at connection points 873. FIG. 18 is a perspective view ofthe coil 870 of FIG. 16 fully opened. As shown, the first set of traces831 of the first coil portion 830 continue to be bent at connectionpoints 873 until the first coil portion 830 is planar with the secondcoil portion 850. Bending of the traces could result in fracturing onthe outside surface thereof, in which case, ultrasonic welding could beused to ensure electrical conductivity. Alternatively, the first andsecond sets of traces 831, 851 could connect to opposing edges of theconnector sheet 871, such that bending could not be required. Stamping(and bending) in this way reduces the amount of scrap generated, therebyincreasing material utilization.

FIG. 19 is an exploded view of a low profile electrical componentassembly 990. More specifically, the low profile electrical componentassembly 990 comprises a substrate 992 (e.g., PET layer), a fillermaterial layer 933 (e.g., rubber, foam, durometer, etc.), a coil 930(e.g., resonant coil), and a protective layer 902. The protective layer902 could be partly translucent and could comprise a tab (e.g., forapplying or removing).

FIG. 20 is a perspective view of the filler material 933 of FIG. 19.Filler material 933 comprises grooves 935 which correspond in size andshape to that of the coil 930. In this way, the coil 930 is nested infiller material 933, which protects the coil shape from bending and/ordeformation. Such an assembly facilitates handling of the coil 930 forsubsequent operations.

For any of the embodiments discussed above, the wireless charging coil(e.g., bifilar coil) could be constructed and then (e.g., at a differentlocation and/or time) the first and second coils of the wirelesscharging coil, whether stacked or planar, could be electricallyconnected to each other in series or parallel depending on electricalrequirements.

Having thus described the system and method in detail, it is to beunderstood that the foregoing description is not intended to limit thespirit or scope thereof. It will be understood that the embodiments ofthe present disclosure described herein are merely exemplary and that aperson skilled in the art may make any variations and modificationwithout departing from the spirit and scope of the disclosure. All suchvariations and modifications, including those discussed above, areintended to be included within the scope of the disclosure.

What is claimed is:
 1. A wireless charging coil comprising: a stampedcoil having a spiral trace, an inside end, and an outside end; a jumper,the jumper electrically connected to the inside end of the stamped coiland extending across the stamped coil; a first layer having an adhesive,the adhesive adhering the stamped coil to the first layer and securingthe stamped coil in place; and a second layer positioned over thestamped coil and adhered to the first layer by the adhesive, wherein thestamped coil is positioned between the first layer and the second layer,and wherein the stamped coil has a fill ratio greater than 65%.
 2. Thewireless charging coil of claim 1, wherein the jumper and the outsideend of the stamped coil extend beyond the first layer and the secondlayer.
 3. The wireless charging coil of claim 1, wherein the outside endof the stamped coil defines a first terminal and at least a portion ofthe jumper defines a second terminal.
 4. The wireless charging coil ofclaim 1, wherein the stamped coil is of a generally rectangular shape.5. The wireless charging coil of claim 1, wherein the second layer is aferrite shield.
 6. The wireless charging coil of claim 5, wherein theadhesive secures the stamped coil in a relative placement to the ferriteshield.
 7. The wireless charging coil of claim 1, wherein the stampedcoil has a fill ratio of approximately 85%.
 8. The wireless chargingcoil of claim 1, wherein the spiral trace has a thickness between 0.003inches and 0.020 inches.
 9. The wireless charging coil of claim 1,wherein the spiral trace has a width between 0.005 inches and 0.250inches.